High-speed impedance relay element



Nov. 7, 1933. s. GOLDSBOROUGH 1,934,663

HIGH SPEED IMPEDANCE RELAY ELEMENT Original Filed May l. 1950 WITNESSES: INVENTOR d l S/y/f/@L'O/@eomdg/y.

@di I WMM/MM ATTORNEY element of a high-speed impedance-responsive re- Patented Nov. 7, 1933 UNITED STATES PATENT OFFICE "HIGH-SPEED IMPEDANCE `RELAY i ELEMENT vania original application May 1, v1930, serial No. i 448,937. Divided and this application February 1, 1933. Serial No. 654,661

l 3 Claims# *(Cl. 175-294) This application is a division of my application Serial No. 448,937, filed May 1, 1930, for Highspeed impedance-responsive relays.

My invention relates to 4relays and relaying systems particularly designed for use with quickacting circuit-breakers for the purpose of increasing the stability of transmission lines, or the ability of such lines to transmit power without loss of synchronism'durin'g fault conditions. My present invention relates to the impedance lay which is sold by the Westinghouse Electric and Manufacturing Company as the type HZ relay. It has been developed to solve the problem of a high-speed relay for use in connection with high-speed breakers to elect the rapid clearing of line faults.y rThis relay is capable of operating in 1 cycle or less on a Gil-cycle system. Selectivity is attained by the employment of the irnpedance principle. This principle has been chosen.

Fig. 2 is across sectional View of one of theV impedance elements@ f The apparatus which is commonly sold under the namel 01": a high-speed impedance' relay, type HZ, consists of va glass-enclosed box or board having a number of v.so-called elements mounted thereon or therein.

Each relay comprises three instantaneously operating high-speed impedance-responsive relayelements 11, 12 and 13, each having a currentresponsive actuating coil 14 and a voltage-responsive restrainingcoil l5.V The iirst impedance element 11 has a pair of normally open contacts 16,

whereas the second and third relay elements l2 and 13 have normally closed contacts 1'7 and 18, respectively. i

The impedancerelay-elements l1, 12 and 13 are constructed to operate as quickly as possible upon an overbalancing ofthe voltage coil .-15 by the current coil 14. VThese relays thus respond to a criticalv ratio of voltage to current, and hence to a critical impedance, or apparent impedance, of the delta phase of the line to which the relay is connected. When the line impedance becomes less kthan a predetermined value, therefore, the' impedance relay-element operates. The second and third impedance elements 12 and v13 are set to operate at a higher critical impedance than the firstl relay element, and hence their voltage coils l5 may be connected in series with each other and intparallel to the voltage coil ofthe first element 11.

Referring to the detailed construction of the impedance elements shown in Figs.'l and 2 of the accompanying drawing, it will be noted that each of these elements comprises a centrally pivoted contact-carrying beam 40 of a non-magnetic inaterial, such asbrass, carrying, at each end, a plunger or armature 41 of magnetic material, preferably of a magnetic material having low remanence and a high maximum permeability at low ilux densities, such as'hipernic, which is an alloy oi approximately 50% nickel, 50% iron and varying quantities of manganese up to 1%. The low remanence 'is desired in order that the armature will have no dysteresis or residual magnetism so that it will loseits flux quickly and completely as soon as the magnetizing force is removed, which is necessaryin order to obtain avery quick action; The high maximum permeability at low flux densities is desirable in order to obtaina strong positive action as soon as the pulls on the two ends of the contact-carrying beam 40 are overbalanced, even though the currents are weak.

The plunger or armature 41 on the contact end of the beam 40 is pulled down by the action of the current coil- 14, whereas the plunger or armature v41 at the other end of the beam is pulled down by the voltage coil 15 which thus opposes the current coil. Both coils are provided with axially adjustable hipernic cores 43 which are screw-threaded Jto/provide the axial adjustment.

The plungers and the beam are made light, so that, once the pull on the current side becomes greater than the pull on the voltage side, the beam moves very quickly and closes the bridging'contactsr 16, in the case of the first impedance element 11, or opens the contacts 17 or 18, in the case of the second and third impedance elements hij 12 and 13. This contact-opening action, as indicated in Fig. 1, is secured by the provision of a micarta finger attached to the contact-carrying end of the beam and pressing down on a leaf spring 46 which carries the bottom contact member of the normally closed contact 17 or 18, the top contact-carrying member being rigidly supported by an insulating block. 47.

The pivoted beam 40 may be provided with a balancing weight 48, as will be obvious.

The plunger or armature 41, which extends into the voltage coil 15, is provided with a non-magnetic pin extension 49 which depends downwardly into a suitable bore in the core screw 43 of this voltage coil. This pin 49 thus serves to center the plunger or armature 41 within the voltage coil 15. The pin 49 also serves as a stop to limit the pulling action of the voltage coil, by means of the resting of the pin 49 against the top of an adjusting screw 50 which projects up through the bottom of the core screw 43 of the voltage coil. Adjustment of the screw 50 thus serves to control the air gap 51 between the bottom of the plunger 41 and the top of the core 43 of the voltage coil 15. This adjustment is commonly made at the factory and not thereafter disturbed,

The current coil 14 and its core screw 43 are adapted to be adjusted by the user of the apparatus. To this end, a tap-changing block is provided comprising a non-conducting block 52 which is provided with a row of perforations 53, each of which is partially filled by a tap-changing terminal 54 which extends part way into the perforations 53 from the back of the insulating block 52. The front of the block 52 is provided with a metal strip 55 having corresponding perforations 56 through any one of which a tap screw 57 may be inserted according to the number of turns which is desired.

By providing taps so that, when moving from one tap to the next higher tap, a geometric progression is made in the number of effective turns of the current coil, and by providing for axial adjustment of the core 43 of the current coil 14, I am enabled to provide for a continuous adjustment of the pull of the current coil over the entire range, including any possible intermediate value. I have also provided a system of marking which effectively correlates these two adjustments. Thus, a series of numbers, as indicated at 58, are assigned to the series of taps on the tapchanging block, and indicated on the face of the block, as shown in Fig. 1, and a vertical-adjustment scale 59 is also provided to indicate the axial adjustment of the core 43 of the current coil 14, and a series of numbers, usually from one to three, are assigned to the vertical scale of the adjusting screw, as indicated at 60 in Fig. 1, the highest number being at the top, corresponding to the shortest air gap between the plunger and the core of the current coil.

The use of this system of markings of the settings of the current coil may be explained as follows:

Since the impedance of the voltage circuit of the relay is the same at all times, it is merely necessary to increase or decrease the pull of the current coil 14 in order to eiect a balance for a larger or smaller impedance, respectively.

The most satisfactory method of arriving at the tap settings is by use of a formula. This formula is as follows:

TS Rv where L is the length of the line up to the socalled balance point at which the impedance element tips over, and Z is the unit impedance of the line. RC is the current transformer ratio. Rv is the potential transformer ratio. 'I' is the number on the relay tap block, as indicated by the scale 58, and S is the number on the vertical core-screw scale 60.

For example, after having obtained the value of TS, T should be obtained by dividing TS by the largest number on the scale S which will yield an even tap number. For instance, if the product TS should come out 36, it is seen that S=2.25 and T:16 gives this product. These taps should be used rather than S=1.125, T=32.

The settings for the second and third impedance elements are obtained in the same manner, using the proper values of LZ.

In the foregoing specification and in the appended claims, the term impedance element or impedance-responsive element, when used without further qualification, refers to any relay-element which picks up at a predetermined impedance or an apparent or arbitrary component of impedance or quantity obtained by dividing any voltage component or quantity by any current component or quantity.

While I have carefully described my new highspeed impedance relay element and explained its design and operation in a single preferred form of embodiment, it will be obvious that various changes and modications may be resorted to without departure from the essential intent and spirit of the invention. I desire, therefore, that the appended claims be accorded the broadest construction consistent with their language and the prior art.

I claim as my invention:

1. A substantially instantaneous impedance-I responsive relay-element of a balanced-plunger type having a non-magnetic intermediately pivoted beam, a magnetizable armature depending from each end thereof, a voltage coil and a current coil embracing the respective armatures and provided with magnetizable cores, said armatures and cores being of a material having low remanence and a high maximum permeability at low ux densities, a tap-changing means for varying the number of turns on said current coil, and means for axially adjusting the core of said current coil, the axial adjustment of the current-coil core cooperating with the adjustments provided for by the taps to give any intermediate adjustment between any two taps.

2. A substantially instantaneous impedanceresponsive relay-element comprising an intermediately pivoted beam, an armature depending from each end, a current coil having an axially adjustable magnetizable core associated with one armature for pulling the beam towards its actuated position, and a voltage coil having a magnetizable core associated with the other armature for pulling the beam towards its inactive position, characterized by a tap-changing block for said current coil, bearing a certain series of numbers opposite its respective taps, and an axial core-position scale for said current coil, bearing a certain series of numbers, said two series of numbers being so chosen that the product of the numbers corresponding to any particular settings of tap-changer and core is always substantially proportional to the ratio of voltage to current at which the beam is overbalanced by the pull of the current coil, the axial scale acting as a kind of Vernier for obtaining intermediate adjustizable core associated with the other armature for pulling the beam towards its inactive position, characterized by a tap-changing block for said current coil, the axial adjustment of the currentcoil core cooperating with the adjustments provided for by the taps to give any intermediate adjustment between any two adjacent taps.

SHIRLEY L. GOLDSBOROUGH. 

